Pyrotechnic compositions



PYROTECHNIC COMPOSITIONS Jean A. M. Brock, St. Louis, Mo., assignor toOlin Mathieson Chemical Corporation, East Alton, 11]., a corporation ofVirginia No Drawing. Filed Apr. 21, 1958, Ser. No. 729,526

7 Claims. (Cl. 52-24) This invention relates to pyrotechnic compositionsand particularly to combination smoke and flare compositions. Varioustypes of pyrotechnic compositions capable of providing large coluds ofsmoke upon combustion are well known as are pyrotechnic compositions forthe production of intense flame. In various situations,'the

desirability of a pyrotechnic composition capable of the simultaneousproduction of huge clouds of smoke together with a brilliant flame haslong been recognized. In previous attempts to provide such combinationsignals, pyrotechnic devices have been developed in which a smokeproducing composition is adjacent to a flare composition. Such a unionof a smoke producing composition with a separate flare composition hasnot been completely satisfactory. The preparation of such devicesrequires special care and involves handling of two separate mixtures. Inaddition, great care must be taken 'to coordinate the burning rates ofthe two compositions to provide satisfactory performance. 7

It is, therefore, an object of this invention to provide novelpyrotechnic compositions capable of simultaneously producing a largevolume of smoke and a brilliant flame. Another object of this inventionis to provide novel combination smoke and flare compositions. A furtherobject of this invention is to provide pyrotechnic compositionsovercoming the disadvantages of the prior art. A more specific object ofthis invention is to provide a combination white smoke and flarecomposition.

In accordance with this invention, these and other .objects areaccomplished by providing combination white Esmoke and flarecompositions containing magnesium, zinc loxide and ammonium perchlorate.Up to about 60% .by weight of the metallic magnesium in thesecompositions can be replaced with magnesium chloride. The substitutionof magnesium chloride as a fuel retards the burning rate of thecompositions and increases smoke evolution. Smoke generation of thesecompositions can also be intensified by the incorporation ofhexachlorethane. The components of these compositions are granular andpreferably have an average particle size of about 80 mesh. However, theparticle size can be varied to control the rate of burning. Thecompositions of this invention are prepared by providing an intimatemixture of the various components which is then packed into suitablecontainers or pyrotechnic devices. The mixtures without a binder can betamped into their containers or alternatively a suitable plastic bindercan be utilized.

The components of the compositions made in accordance with thisinvention must be present in substantially stoichiometric proportions.However, the proportions can be varied to alter the characteristics ofthe compositions. Thus, the burning rate, flame intensity, smokegeneration, and other properties of these compositions can be modifiedWithin limits by altering the proportions between the reactants.

In order to increase the smoke forming capabilities of the compositionswhile retaining suitable flame intensity properties, up to about 60% byweight of the metallic M 2,939,780 Patented June .1960

magnesium can be replaced with magnesium chloride. The magnesiumchloride serves both as a fuel and a chloride donor, and is preferablypresent in amounts-substantially equal to the metallic magnesium.Amounts of magnesium chloride slightly in excess of the magnesium can beused, but it has been found that when more than about 60% of themagnesium is replaced by magnesium chloride, the resultant compositionburns with no flame and produces only a thin smoke.

[It is believed that the success of the novel composition of the presentinvention is dependent upon reactions which may be typified by thefollowing chemical equations:

While all observations of the compositions indicate that upon combustionthey react in the above manner, it is fully recognized that otherreactions may actually occur. In any event, the molecular ratios of thereactants remain constant. Thus, it is to be distinctly understood thatthe present invention is not limited to the above reactions.

When the compositions consist of magnesium, zinc oxide, and ammoniumperchlorate, it has been found that the proportions of the ingredientsmust be maintained within the following approximate percentage ranges:

Percent Magnesium 27-50 Zinc oxide 15-30 Ammonium perchlorate 30-55Preferably the composition contains about 35% mag nesium, about 17% zincoxide and about 49% ammonium perchlorate. These and other percentagesthroughout the specification are based on the relative weights of thecomponents in the compositions.

When the metallic magnesium fuel is partially replaced by magnesiumchloride, it is preferred to employ a mixture containing approximately25% magnesium, 25% magnesium chloride, 20% zinc oxide and about 30%ammonium perchlorate, but the proportions can vary generally asindicated above with up to about 60% of the magnesium being replacedwith magnesium chloride. I v

In those instances where hexachlorethane is added to compositionscontaining magnesium as a fuel to intensify the smoke evolution, it ispreferred to use a composition containing about 12% magnesium, about 36%zinc oxide, about 35% hexachlorethane and about 17% ammoniumperchlorate, but the proportions can vary "Percent Magnesium 10-25 Zincoxide 30-40 Hexachlorethane 30-40 Ammonium perchlorate 15-25 Whenproportions of metallic magnesium outside of the ranges set forth aboveare used, undesirable results are obtained. For example, when too littlemagnesium is used, the intensity of the flame is severely reduced andexcessive amounts of magnesium result in very rapid burningcompositions.

The compositions of the present invention rely for smoke generation uponthe formation of zinc chloride which can be supplemented by thecombustion of hexachlorethane. Thus, in each instance the amount of zincoxide present should be suflicient to provide adeproperties of thecomposition. Amounts of .hexachlorethane in excess of 40% normally donot improve the properties of themixtures. p 7 v a r The formulationsmade in accordance'with this invention can readily be adjusted toinclude a plastic binder Upon ignition, the mixture burned for about 50seconds such as polyvinyl acetate, ,polyvinyl chloride copolymers,polyesters, epoxy, and the like. Up to about 5% of such binderscanbeadded without changing the composition. If more binder is desired, itcanbe readily added by readjusting the remaining components. Since thecombination smoke and flare compositions normally have a positive oxygenbalance, the addition of more binder can be accomplished withoutdifliculty.

. Theinvention will be more fully understood by refer- :ence to thefollowing specific examples of preferred embodiments thereof. In theseembodiments, all propor tions are expressed in parts by weight. 1

' About 12 parts of metallic magnesium having a granulation. ofabout 40mesh were mixed with about 36 parts .of zinc oxide, about 35 parts ofhexachlorethane, and about 17 parts of ammonium perchlorate. Thesematerials were thoroughly mixed together with about 5 parts of polyvinylacetate which served to bind the components together. The uniformmixture was then charged into metal cans about 2% inches in diameter andabout 12%; inches high. The mixture was introduced in two increments-andpressed with a 25,000 pound load. An ignition pellet containing about20% black powder, about 40% potassium nitrate, and about 40% silicon wasattached to the upper surface of the ignition composition ,by means of anitrocellulose lacquer. The assembly was then adaptable for. ignition bya squib, quick match or other conventional means. Upon ignition, thesmoke and .flame composition burned for about seconds with a with abrilliant white flame and developed a large cloud of heavy white smoke.

While the above examples describe particular methods of formulating thecompositions of this invention and also recite charging them into aspecific type of container, it will be readily understoodthat otherformulating means can be utilized and that the compositions can beprovided with any suitable type of container. Thus, the compositions cancontain sufiicient binder to provide a mix that can be molded, extruded,or otherwise shaped and the consolidated body of the composition canthen be provided with a suitable wrap-per. Also, any of the conventionalpyrotechnic ignition means can be employed to ignite these compositions.

Having thus described the invention, what is claimed is:

- 1. A.combinati on white smoke and flare composition consistingessentially of substantially stoichiometric proportions of magnesium,zinc oxide and ammonium perchlorate for the formation of magnesiumoxide, zinc chloride, nitrogen, and water as reaction products.

2. A combination white smoke and flare composition consistingessentially of substantially stoichiometric'proportions of magnesium,magnesium chloride, zinc oxide,

and ammonium perchlorate for the formation of magnesium oxide, zincchloride, and ammonium chloride as reaction products.

3. A combination white smoke and flare composition consistingessentially of substantially stoichiometric proportions of magnesium,zinc oxide, ammonium perchlorate, and hexachlorethane for the formationof magnesium oxide, zinc chloride, carbon dioxide and ammonium chlorideas reaction products.

4.. The composition of claim 1 in which a portion of the magnesium notin excess of about 60 percent is replaced with magnesium chloride.

brilliant white flame and developed a large cloud of .heavy white smoke..Another batch of a combination smoke and flare composition was preparedin accordance with this invention.

-In/this embodiment, a portion of the metallic magnesium was replacedwith magnesium chloride. This formulation .had the following approximatecomposition:

'25 magnesium 25% magnesium chloride 20% zinc oxide I 30% ammoniumperchlorate 5. The composition of claim 3 in which a portion of themagnesium not in excess of about 60 percent is replaced with magnesiumchloride.

6. A combination White smoke and flare composition consistingessentially of between about 30 percent and about 45 percent by weightmagnesium, between about 15, percent and about 30 percent by weight zincoxide,

and between about 35 percent and about 50 percent by; weight ammoniumperchlorate.

, 7. A combination white smoke and flare composition consistingessentially of between about 10 percent and about 25. percentby weightmagnesium, between about 30 percent and about 40 percent by weight zincoxide, between about 30 percent and about 40 percent by weighthexachlorethane, and between about 15 percent and about 25 percent byweight ammonium perchlorate.

References Cited in the file of this patent UNITED STATES PATENTS2,416,639 Pearsall Feb. 25, 1947 FOREIGN PATENTS 127,031 Great BritainMay 29, 1919

3. A COMBINATION WHITE SMOKE AND FLARE COMPOSITION CONSISTINGESSENTIALLY OF SUBSTANTIALLY STOICHIOMETRIC PROPORTIONS OF MAGNESIUM,ZINC OXIDE, AMMONIUM PERCHLORATE, AND HEXACHLORETHANE FOR THE FORMATIONOF MAGNESIUM OXIDE, ZINC CHLORIDE, CARBON DIOXIDE AND AMMONIUM CHLORIDEAS REACTION PRODUCTS.